Probing ISM and Dust Abundance with X-rays

Lia Corrales (Columbia)

X-ray spectroscopy reveals the presence and abundance of heavy elements
in space. Many of these -- such as carbon, oxygen, and iron -- are
common contributors to interstellar dust. Absorption edges in an X-ray
spectrum directly probe the abundance of elements in gas and dust form.
The spectrum from dust scattering provides abundances for grains only.
These two pieces of information directly measure the depletion of
gas-phase metals into dust grains and test conventional assumptions
regarding ISM abundances. We demonstrate this technique with
observations of Cygnus X-3 made with the Chandra High Energy
Transmission Grating.